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A221468
The Collatz (3x+1) iteration in A220145 converted to decimal.
2
1, 2, 133, 4, 33, 266, 67733, 8, 541865, 66, 16933, 532, 529, 135466, 135253, 16, 4233, 1083730, 1083717, 132, 129, 33866, 33813, 1064, 8669737, 1058, 2678946987458595510314019806849701, 270932, 270929, 270506, 83717093358081109697313118964053, 32, 69357897
OFFSET
1,2
COMMENTS
Sequence A005186 tells how many of these numbers are in [2^n, 2^(n+1)-1].
From Rémy Sigrist, Aug 19 2017: (Start)
a(2^n) = 2^n for any n >= 0.
A000120(a(n)) - 1 = A006667(n) for any n > 0.
A070939(a(n)) - 1 = A006577(n) for any n > 0.
All terms are Fibbinary numbers (A003714).
(End)
MATHEMATICA
Table[FromDigits[#, 2] &@ Boole@ OddQ@ Reverse@ NestWhileList[If[EvenQ@ #, #/2, 3 # + 1] &, n, # > 1 &], {n, 33}] (* Michael De Vlieger, Aug 19 2017 *)
PROG
(PARI) a(n) = my (v=0, p=1); while (n>1, if (n%2, n = 3*n+1; v += p, n = n/2); p *= 2); return (p+v) \\ Rémy Sigrist, Aug 19 2017
KEYWORD
nonn,base,look
AUTHOR
T. D. Noe, Jan 17 2013
STATUS
approved